如何使用供应商？

Question

经过几天尝试改变我的方法，我终于得到了结果。但这是我的问题：每次我重新启动应用程序时，我都有一个从 main 调用的包装器。我想在我的包装器中使用它 class:

if(FirebaseAuth.instance.currentUser.emailVerified){}

这是我目前的包装 class：

import 'package:flutter/material.dart';
import 'package:projectandroidstudiodenya/seitenleiste/homepage.dart';
import 'package:provider/provider.dart';
import 'authenticate/authenticate.dart';
import 'models/user.dart';



class Wrapper extends StatelessWidget {
  static const route='/Wrapper';
  

  @override
  Widget build(BuildContext context) {
    //Auth.auth().currentUser.isEmailVerified;
    //final user = Provider.of<UserCredential>(context);

    final user = Provider.of<User>(context);

    if(user == null){
      return Authenticate();
    }else {
      return Homepage();
    }
    //return Home or Authenticate widget
  }
}

它应该是这样的：

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:projectandroidstudiodenya/seitenleiste/homepage.dart';
import 'package:provider/provider.dart';
import 'authenticate/authenticate.dart';
import 'models/user.dart';



class Wrapper extends StatelessWidget {
  static const route='/Wrapper';


  @override
  Widget build(BuildContext context) {
    //Auth.auth().currentUser.isEmailVerified;
    //final user = Provider.of<UserCredential>(context);

    final user = Provider.of<User>(context);

    if(user == null){
      return Authenticate();
    }else if(FirebaseAuth.instance.currentUser.emailVerified){
      return Homepage();
    }
    //return Home or Authenticate widget
  }
}

所以你可以看到我打电话给 user.emailVerified。但这是错误的，我真正需要的是您在顶部看到的内容。但是当我尝试更改我的代码时，我收到了这个错误

The name 'User' is defined in the libraries 'package:firebase_auth/firebase_auth.dart' and 'package:projectandroidstudiodenya/models/user.dart'.

我真的不知道该怎么做以及如何改变。

这是我的授权class:


import 'dart:async';

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/cupertino.dart';
import 'package:projectandroidstudiodenya/authenticate/register.dart';
import 'package:projectandroidstudiodenya/authenticate/signin.dart';
import 'package:projectandroidstudiodenya/authenticate/verifyemail.dart';

import 'package:projectandroidstudiodenya/models/user.dart' as Model;
import 'package:projectandroidstudiodenya/services/database.dart';

import 'database.dart';
import 'database.dart';
import 'database.dart';

class AuthService {
 // final FirebaseAuth _auth = FirebaseAuth.instance.currentUser as FirebaseAuth;
  final FirebaseAuth _auth = FirebaseAuth.instance  ;


  String error;
  String result="";



  //create user obj based on FirebasedUser
  Model.Userr _userFromFirebaseUser(User user) {
    return user != null ? Model.Userr(uid: user.uid) : null;
  }

  Stream <Model.Userr> get user{
    return FirebaseAuth.instance.authStateChanges().map(_userFromFirebaseUser);
}

//SIGNOUT
  Future<void> signOut() async {
    await FirebaseAuth.instance.signOut();
  }
  //sign in anon
  Future signInAnon() async {
    try {
      UserCredential result = await _auth.signInAnonymously();
      User user = result.user;
      return _userFromFirebaseUser(user);
    } catch (e) {
      print(e.toString());
      return null;
    }
  }
  //sign in with passwort and email
  Future signIN(String email, String password) async {
    try {
      //if (FirebaseAuth.instance.currentUser.emailVerified) {print('fuckyooooooo');

      (await _auth.signInWithEmailAndPassword(
          email: email.trim(), password: password)).user?.emailVerified;
    }

      on FirebaseAuthException catch (e) {
      switch (e.code) {
        case 'invalid-email':
          {
            return 'Email is not valid';
          }
        case 'user-disabled':
          {
            return 'Account is not active';
          }
        case 'user-not-found':
          {
            return 'No user found';
          }
        case 'wrong-password':
          {
            return 'wrong password';
          }
        default:
          {
            return 'Please verify you account and restart the App';
          }
      }

    }

      return null;




  }






//register with passwort an email
  Future signUp(String email, String password,) async {
    try {

      UserCredential result =await _auth.createUserWithEmailAndPassword(
          email: email, password: password);
          result.user?.sendEmailVerification();
          User user =result?.user;
      await DatbaseService(uid:user.uid).updateUserData('0','new crew member','100','dfdssf');
          return ;

      //user.sendEmailVerification();
     // ( await DatbaseService(uid:user).updateUserData('0','new crew member','100','dfdssf')).user.uid;;
    } on FirebaseAuthException catch (e) {
      switch (e.code) {
        case 'invalid-email':
          {
            return 'Email is not valid';
          }
        case 'user-disabled':
          {
            return 'Account is not active';
          }
        case 'user-not-found':
          {
            return 'No user found';
          }
        case 'wrong-password':
          {
            return 'wrong password';
          }
        default:
          {
            return 'Unexpected error!';
          }
      }
    }
    return null;
  }



  Model.Userr getCurrentUser(User user) {

    return user != null ? Model.Userr() : null;
  }


  //resetpassword
  Future sendPasswordResetEmail(String email) async {
    try {
      return await _auth.sendPasswordResetEmail(email: email);
    } on FirebaseAuthException catch (e) {
      switch (e.code) {
        case 'invalid-email':
          {
            return 'Email is not valid';
          }
        case 'user-disabled':
          {
            return 'Account is not active';
          }
        case 'user-not-found':
          {
            return 'No user found';
          }
        case 'wrong-password':
          {
            return 'wrong password';
          }
        default:
          {
            return 'Unexpected error!';
          }
          return null;
      }
    }
  }
}

这是我的主要内容


void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context){
   return
      StreamProvider<Userr>.value(

        child: MaterialApp(
                  debugShowCheckedModeBanner: false,
                  title:'Appbar Scaffold',
                  theme: ThemeData(
                    scaffoldBackgroundColor: Colors.white,
                    primaryColor: Colors.white,
                  ),
                  //home: Homepage(),
                  //initialRoute: '/',
               // initialRoute: FirebaseAuth.instance.currentUser==null?LoginScreen():Homepage.route(),
                  routes:{'/':(_)=>Wrapper(),
                   Homepage.route:(_)=> Homepage(),

                    Beitraegedieichmag.route:(_)=> Beitraegedieichmag(),
                    MeinAccount.route:(_)=> MeinAccount(),
                    MeineBeitraege.route:(_)=>MeineBeitraege(),
                    MeineFreunde.route:(_)=> MeineFreunde(),
                    Nachrchten.route:(_)=> Nachrchten(),
                    LoginScreen.route:(_)=> LoginScreen(),
                  } ,

这是错误：

======== Exception caught by widgets library =======================================================
The following ProviderNotFoundException was thrown building Wrapper(dirty):
Error: Could not find the correct Provider<User> above this Wrapper Widget

This happens because you used a `BuildContext` that does not include the provider
of your choice. There are a few common scenarios:

- You added a new provider in your `main.dart` and performed a hot-reload.
  To fix, perform a hot-restart.

- The provider you are trying to read is in a different route.

  Providers are "scoped". So if you insert of provider inside a route, then
  other routes will not be able to access that provider.

- You used a `BuildContext` that is an ancestor of the provider you are trying to read.

  Make sure that Wrapper is under your MultiProvider/Provider<User>.
  This usually happens when you are creating a provider and trying to read it immediately.

  For example, instead of:


  Widget build(BuildContext context) {
    return Provider<Example>(
      create: (_) => Example(),
      // Will throw a ProviderNotFoundError, because `context` is associated
      // to the widget that is the parent of `Provider<Example>`
      child: Text(context.watch<Example>()),
    ),
  }
  

  consider using `builder` like so:

  
  Widget build(BuildContext context) {
    return Provider<Example>(
      create: (_) => Example(),
      // we use `builder` to obtain a new `BuildContext` that has access to the provider
      builder: (context) {
        // No longer throws
        return Text(context.watch<Example>()),
      }
    ),
  }
 

If none of these solutions work, consider asking for help on Whosebug:
https://whosebug.com/questions/tagged/flutter

The relevant error-causing widget was: 
  Wrapper file:///Users/yavuzatmaca/StudioProjects/projectandroidstudiodenya/lib/main.dart:44:36
When the exception was thrown, this was the stack: 
#0      Provider._inheritedElementOf (package:provider/src/provider.dart:332:7)
#1      Provider.of (package:provider/src/provider.dart:284:30)
#2      Wrapper.build (package:projectandroidstudiodenya/wrapper.dart:20:27)
#3      StatelessElement.build (package:flutter/src/widgets/framework.dart:4661:28)
#4      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4587:15)

====================================================================================================
Reloaded 16 of 687 libraries in 640ms.

这是我的用户class


import 'package:flutter/cupertino.dart';

class Userr{

 final String uid;

 Userr({this.uid});



}

现在的错误是：


======== Exception caught by widgets library =======================================================
The following NoSuchMethodError was thrown building Wrapper(dirty, dependencies: [_InheritedProviderScope<Userr>]):
The getter 'emailVerified' was called on null.
Receiver: null
Tried calling: emailVerified

The relevant error-causing widget was: 
  Wrapper file:///Users/yavuzatmaca/StudioProjects/projectandroidstudiodenya/lib/main.dart:47:36
When the exception was thrown, this was the stack: 
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
#1      Wrapper.build (package:projectandroidstudiodenya/wrapper.dart:22:42)
#2      StatelessElement.build (package:flutter/src/widgets/framework.dart:4661:28)
#3      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4587:15)
#4      Element.rebuild (package:flutter/src/widgets/framework.dart:4281:5)
...
====================================================================================================

======== Exception caught by widgets library =======================================================
The following NoSuchMethodError was thrown building Wrapper(dirty, dependencies: [_InheritedProviderScope<Userr>]):
The getter 'emailVerified' was called on null.
Receiver: null
Tried calling: emailVerified

The relevant error-causing widget was: 
  Wrapper file:///Users/name/StudioProjects/projectname/lib/main.dart:47:36
When the exception was thrown, this was the stack: 
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
#1      Wrapper.build (package:projectname/wrapper.dart:22:42)
#2      StatelessElement.build (package:flutter/src/widgets/framework.dart:4661:28)
#3      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4587:15)
#4      Element.rebuild (package:flutter/src/widgets/framework.dart:4281:5)
...
====================================================================================================

Answer 1

试试这个：

class Wrapper extends StatelessWidget {
  static const route='/Wrapper';

  @override
  Widget build(BuildContext context) {

    final user = Provider.of<Userr>(context);

    if(user == null){
      return Authenticate();
    }else if(FirebaseAuth.instance.currentUser.emailVerified){
      return Homepage();
    }
    //return Home or Authenticate widget
  }}

Main.dart:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(StreamProvider<Userr>.value(
    value: AuthService().user,
    child: MaterialApp(
      home: MyApp(),
    ),
  ));
}
class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      ...
    );
  }
}

如何使用供应商？

How to use provider?

sign

google-authentication

firebase

flutter